How to set a value in last element of array and push a new object into that array at the same time in mongoose?

Question

"pmsStatus": [
        {
          status: 0,
          fromTimeStamp: "12:40:50",
          reason: "no crane",
          toTimeStamp: "13:40:50"
        },
        {
          status: 1,
          fromTimeStamp: "13:40:50",
          toTimeStamp: "14:40:50"
        },
        {
          status: 0,
          fromTimeStamp: "14:40:50",
          toTimeStamp: "15:40:50",
          reason: "breakfast",
          
        }
]

In, consider this as a mongodb collection. And I need to make findOneAndUpdate operation on this. Not on the same status, but status should be different. If the same status we get means, it should not perform any update operation. If the status is different from previous means it should perform update operation. If status we get to store into collection is 1 and the status of previous last element of object is 0, then toTimeStamp should be added wth current time to last object. And for newly stored object's status is 0 and fromTimeStamp should be added with current time(i,e) the toTeStamp of last element and FromTimeStamp of current element is always same

---

My code

pmsStatus.findOneAndUpdate(
                        {_id}
                        , {
                            $push: {
                                dataP
                            }
                        })

I know the above code is not proper, but please help me. I'm a beginner to mongodb. Thank you

Answer 1

If you are using MongoDB version >= 4.4 then try this solution:

Logic to add two timestamps of format "HH:MM:SS" can be found here.

let newObj = {
    status: 1,
    fromTimeStamp: "14:40:50",
    toTimeStamp: "15:40:50",
    reason: "breakfast",

};

db.testCollection.findOneAndUpdate(
    {},
    [
        {
            $set: {
                pmsStatus: {
                    $function: {
                        body: function(pmsStatus, newObj) {
                            let lastObj = pmsStatus[pmsStatus.length - 1];
                            
                            if(newObj.status != lastObj.stattus) {
                                let result;
                                // Logic to add timestamps and store it in result
                                pmsStatus[pmsStatus.length - 1] = result;
                            }
                            
                            return pmsStatus;
                        },
                        args: ["$pmsStatus", newObj],
                        lang: "js"
                    }
                }
            }
        }
    ],
    {
        returnNewDocument: true
    }
);